Absorbance/Transmission NIST reference standards

Absorbance/Transmission

For the measurement of this fundamental parameter, Starna® offers you the choice of either sealed cell, or filter materials. Please note that your selection process should not only include the wavelength(s) required, but also the spectral bandwidth (SBW) of your spectrophotometer. Use of the reference materials outside the SBW range detailed is not excluded, but variations from the certified values may be observe

Potassium Dichromate -
UV Absorbance and Linearity
Description: Potassium dichromate from NIST (SRM 935a) in 0.001M perchloric acid.
Primary Usage: Testing absorbance scale and linearity in the UV region.
Useable range: 235 nm to 350 nm, instruments with a SBW of 2 nm or less.
Physical Configuration: UV quartz cells that have been permanently heat sealed.

Potassium Dichromate – UV Absorbance and Linearity
Product Description:
The use of potassium dichromate solvated in dilute perchloric acid is an established and well recognised method for the validation of the absorbance scale and linearity of a spectrophotometer in the UV region.
W hen prepared in 0.001M perchloric acid, potassium dichromate gives a spectral scan containing characteristic peaks at 257 nm and 350 nm, and troughs at 235 nm and 313 nm. Within the concentration range 20-100 mg/l, if the absorbance scale of a narrow SBW (< 2 nm) spectrophotometer is linear, the apparent absorbances of a series of concentrations will be a linear function of concentration.
RM-0204060810 set:

Consists of one blank (0.001M perchloric acid) and five increasing concentrations, with nominal values of 20 mg/l, 40 mg/l, 60 mg/l, 80 mg/l, and 100 mg/l.
Typical values obtained:

Wavelength .235 nm 257 nm 313 nm 350 nm

20 mg/l 0.240 0.281 0.095 0.211

40 mg/l 0.477 0.556 0.186 0.415

60 mg/l 0.730 0.849 0.284 0.631

80 mg/l 0.988 1.149 0.384 0.852

100 mg/l 1.229 1.433 0.477 1.061

All Starna® potassium dichromate cells are prepared using the solid NIST primary material (SRM 935a), prepared at the solution concentrations described in NIST Special Publication 260-54. After filling under controlled conditions, the cells are then permanently sealed by heat fusion and the values certified by the procedure described below.
Calibration procedure:
Traceability:
•All Starna® potassium dichromate cells are prepared using the solid NIST primary material (SRM 935a), prepared at the solution concentrations described in and Use of Acidic Potassium Dichromate Solutions as an Ultraviolet Absorbance Standard – SRM 935” (NIST Special Publication 260-54).

• Primary instrumental linearity is established using the Double Aperture method.
•Additional traceability links to NIST primary materials are established using SRM 930e and SRM 1930 neutral density glass filters.
Use:
•All appropriate fundamental parameters and procedures relating to measurement, handling and storage are fully documented on the certificate supplied with each Certified Reference Material (see MSDS)

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